LFS says LS is useless without undergravel filter???


LFS has stated that LS is pretty much useless unless you are running a undergravel filter. just wondering what everyone thinks about this. i know that most people have moved away from this type of filter and are still using LS.


Maybe your LFS should make the oceans aware of this... They have been that way since the beginning of time. I run a CC with an undergravel filter, but next tank will be a DSB no underground filter. With some of the fine sand available today, it would sink right through the UG filter rendering it useless.
Just my 2 cents worth.


i know they are just trying to get in my wallet, but just wondering what the board thought about their statement. see what kind of LFS i have to deal with :(


Hey BenTrue,
Give me your LFS's #....I want to call them and ask about their sand over ugf setup! :D That would be a hoot to watch! :cool:


Well you see, here's the thing, the thing is that if you put the sand on top of the undergravel -which has slit in it to let water flow- the sand will eventually work it way down under the undergravel filter. In the end you will just end up with a "shallower-looking" sand bed, with a piece of plastic in it. Unless the pets store was talking about using a plenum, which some people think an undergravel filter can be used for, but thats not really correct. And plenum setups are very difficult to setup up correctly and have it work effectively for a long period of time.


You might want to find a new LFS. LR, LS, and a skimmer is plenty filtration. The LFS should have known that the UG would plug because of the paritcle size of the sand not allowing enough water flow.


While I don't agree with the LFS guy, he might have been referring to a plenum, which is similar to an under gravel filter. The difference is that a plenum does not have lift tubes. It also uses a fiberglass mesh over the grid. Some people, myself included, believe that a sand bed will be more efficient with a plenum. A plenum will help increase diffusion (slow circulation) between the bulk water above the sand bed, and the space under the sand. A DSB directly on the bottom of the tank will not have much diffusion at all below about the top 1 inch. There will be people who disagree with me on this, but I stand by my statement.


Active Member
I agree wit you Sonny. I run a plenum system in my 29gal reef.
But to answer you question, you LFS is wack. Most LFS don't have employees that are knowledgable in the hobby of reef keeping.


I agree, I bet it was someone who confused a UGF with a plenum. Although you can use some sand with a UGF it needs to be a bigger mixture. I use the CaribSea reaflor sand on my UGF's. Some people in here use DSB's, some use wet/dry's, I use UGF's with refugiums, or skimmers if it is a fish only tank. I think this works out much better. I do believe the person was referring to plenum though.


New Member
I actually heard from an employee that an undergravel filter may cause your tank to crash becasue of a build up of "gunk" :) at the bottom....is this true? I dont have one in mine, Im just wondering of the validity of his statements.


About the crash statement, I have not found that to be true. I have been running my tank for over 5 years with an undergravels filter. (my wife says it has been over 10 yrs., how time flies when you are having fun.) I have not had any crashes yet, and have 0 nitrates. All I need is a lighting upgrade, (and more corals) other than that everything is well. If I look under the UGF from the bottom of the tank, yes there is some "silt/gunk", but I am sure that is normal.